Why Are More Alloys Not Jj Rated?

[jimmyjames]

Hello all.

Just a question really, firstly how many are running JJ rated and your experience with them against buckles and cracks agains those using normal J rated alloys with the same experience. I have had double figures of alloys on my T4 some of which are massively load rated and have cracked due to not having the additional J profile on the inner edge which has happened more than once. My current JJ rated BBS splits take a hammering every day and have always balanced well han held air. Why oh why are more of the heavier rated rims not JJ rated, they are so much better.

Hope this all makes sense

 

[jimmyjames]

U'm guessing nobody has clue what i'm on about. Here is the inside of a JJ rim note the inner profile shape giving reinforcement.


Here is a normal J rated rim where all the strength is on the inner lip hence so many sets seem to crack in this area and lose pressure.



I tried this on the T4 forum and not many people knew what the difference was until it was explained.

 

[Tourershine]

I've spend years researching wheels, and the combination of decades since owning a T6 and all the complex issues us commercial boys have when it comes to that old 'wheel' subject, but i've never heard of the JJ rating.

In my experience, load rating means bugger all if you're buying alloys from dubious sources. Cheap junk is exactly that, cheap junk. They may be rated high enough to fit to what ever you're fitting too, but a few of our lovely British potholes and they crack, or buckle rather easily. Couple that with rubber band tyres and that process is even quicker.
Simple fact of life is always price. Price is why most of us don't run forged wheels, or Air suspension. There probably are many wheels that are as you say JJ rated, but they are out the reach of a normal/sensible commercial owners wallet, and left solely to the show Kings and Queens, which there isn't a huge amount of owners in here sadly.

Welcome to the forum.


Edit:
I just had a quick dig around to try and educate myself, and from what I can see, the J rating refers to the shape of the wheels inner flange, and JJ refers to 4x4/passenger vehicle.

 

[foggy3061]

As a way of easier demonstrating J vs JJ:

 

[Loz]

I don’t see how this has anything to do with the strengthening of the wheel, just the ability to keep the tyre on the rim.

 

[jimmyjames]

I don’t see how this has anything to do with the strengthening of the wheel, just the ability to keep the tyre on the rim.

Tyre bead is there regardless of the rating because it is a requirement, the ridge sits after the tyre bead moving towards the face of the wheel as in the original pictures ant takes some of the strain away from the inner lip where most wheels crack. Maybe i have got the wrong end of the stick but i have owned a couple of sets of rims with a support ridge on the inside (genuine BBS and LM replicas) and both times they have been JJ rated. Funilly enough the diagram posted mentions 4X4 rims however none of the factory Range Rover or X5 rims have it hence they are normally welded up buckled junk when driven on poor roads around me. Overly stiff suspension i know has an impact on the longevity, guilty as charged on the old T4 as it was hovering on the bump stops at its lowest point, now raised on decent springs for the sake of my back and the wheels.

Most likely its not done due to the cost of manufacture which is a real shame!

 

[Loz]

The JJ rating has no bearing on the thickness of the material of the rim and steels and alloys will also have different strength.

As there is little in the way of standards for wheel manufacture here in the UK, I personally look for wheels with a TÜV rating.

 

[jimmyjames]

The JJ rating has no bearing on the thickness of the material of the rim and steels and alloys will also have different strength.

As there is little in the way of standards for wheel manufacture here in the UK, I personally look for wheels with a TÜV rating.

Very true, it's the shape not the thickness which gives the extra strength rather than all support for the inner rim being on the inner lip, the same theory as the ridges in the floor of our vans.

 

[jimmyjames]

Well some more research done and it seems, as mentioned before by @foggy3061 that the JJ rating has nothing to do with the ridge on the inner rim, seems its really quite random. Question is still there though as to why more manufacturers dont include this on the design as it makes a massive difference in my experience.

 

[RedUn]

Cost